Deep brain stimulation (DBS) leads are used to stimulate nerve structures in specific areas of the brain to either excite or inhibit cell activity. A stimulation lead is implanted at a precise location within the brain using CT or MRI imaging techniques and stereotactic guidance. Once implanted, the stimulation lead delivers electrical stimulation to produce nerve impulses that inhibit symptoms of a brain disorder. For example, deep brain stimulation can be effective in the management of chronic pain of neuropathic and or nociceptive origin. In addition, deep brain stimulation can be used to treat movement disorders, such as Parkinsons Disease, as well as epilepsy and psychiatric disorders.
Precise placement of the stimulation lead within the brain is extremely important. In some applications, the stimulation lead must be positioned to deliver stimulation exclusively to a very small brain target without stimulating adjacent brain tissue. Precision is extremely important, for example, in SubThalamic Nucleus (STN) stimulation and Globus Pallidus internal (Gpi) stimulation. If stimulation is not delivered with precision to a desired brain target, adjoining areas may likewise be stimulated, leading to side effects that are not well tolerated by the patient.
Also, existing deep brain stimulation leads are typically equipped with cylindrical electrode rings. Stimulation current spreads approximately spherically around the cylindrical electrodes in a homogeneous and isotropic medium. In this situation, the electrode contact is the center of the sphere. However, the three-dimensional, functional structures of the brain may not coincide with the approximately spherical configuration of the stimulation current. As a result, the shape of the stimulation current can make localized stimulation of a desired target difficult.
Existing stimulation leads and positioning techniques can be limited in their ability to effect precise localized stimulation of very small brain targets. Accordingly, there is a need for deep brain stimulation leads that are better suited to stimulate selected small brain targets on a exclusive basis. More generally, there is a need for deep brain stimulation leads capable of delivering appropriate stimulation to very small brain targets without causing intolerable side effects.
Others have developed electrical leads for delivery of stimulation to localized regions in the human body. Unfortunately, the effectiveness of such leads has been challenged by applications involving extremely small targets within the human brain. Table 1 lists a number of documents that disclose electrical leads designed to achieve electrical stimulation in small, localized regions.
TABLE 1Patent NumberInventorsTitleU.S. Pat. No. 5,843,148Gijsbers et al.High Resolution BrainStimulation Lead and Methodof UseU.S. Pat. No. 5,643,339HolsheimerMultichannel Apparatus forEpidural Spinal CordStimulationU.S. Pat. No. 5,501,703HolsheimerMultichannel Apparatus forEpidural Spinal CordStimulationUS/01/27336Gielen et al.Combined Micro-macro BrainStimulation Lead and Methodof Using SameU.S. Pat. No. 4,961,434StypulkowskiArray of Recessed RadiallyOriented Bipolar ElectrodesU.S. Pat. No. 5,000,194van den HonertArray of Bipolar ElectrodesU.S. Pat. No. 5,927,277Baudino et al.Method and Apparatus forSecuring Probes Within aBurr Hole
All documents listed in Table 1 above are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the techniques of the present invention.